The assessment of the condition or the performance of bearings is conventionally performed by checking the free play of the bearing, the condition of lubricants or by measuring the coefficient of friction of the bearing. However, many bearings when installed in their operating environment prevent or inhibit effective assessment of these performance indicators.
For example, it can be difficult to determine the coefficient of friction of a bearing if it is installed as part of a mechanism where the individual contribution of that bearing to a complex system is not easily discernable.
Furthermore, it may not be easy to assess the condition of the lubricant as the bearing may be installed in an inaccessible environment. Free play may be also very difficult to detect in the context of an assembled mechanism or may be masked completely by a seized bearing rotating within its housing or about a shaft.
These issues are particularly acute in the context of aircraft structures. Aircraft are subject to significantly more stringent reliability and performance constraints than most other complex pieces of machinery. Therefore, reliable and accurate mechanisms for monitoring the performance of bearings are essential.
A number of the bearings involved in the operation of aircraft control surfaces are frequently rendered inaccessible by other aircraft components and may also be part of more complex structures that obscure the behaviour of any individual bearing. For example, a hinge in a complex high-lift device may be part of a structure incorporating a number of bearings and the indicators of either bearing failure or incipient bearing failure may be masked by the overall operation of the device. Further, the behaviour of failing bearings can also be dependant on the physical conditions under which they are operating. Thus, a defective bearing may behave differently when the aircraft is in its operating environment and the bearings are loaded.
It is usually therefore necessary to partially or completely disassemble the assembly containing the bearing in order to determine its condition.
The present invention seeks to overcome or ameliorate the abovementioned problems.